The purpose of this standard is to define the different concepts of masses required for the design, testing, delivery acceptance, marking and operation of rail vehicles and to provide a single reference value for the defined vehicle states. The masses defined in this standard are as follows: dead mass; design mass; design mass, in working order; design mass under normal payload; design mass under exceptional payload; operational mass; operational mass, in working order; operational mass under normal payload. These masses are defined regarding the whole vehicle, but they can also apply to a part of the latter; in this case, their designation shall be completed by the indication of the relevant vehicle part. These reference masses should be used directly. However, other masses may be required to meet the specific requirements of other standards. In these cases these masses will need to be identified in different terms or by factoring theses reference masses.